Co-Localization of Gastrointestinal Stromal Tumors (GIST) and Peritoneal Mesothelioma: A Case Series

Abstract

Purpose: Gastrointestinal stromal tumor (GIST) is associated with increased risk of additional cancers. In this study, synchronous GIST, and peritoneal mesothelioma (PM) were characterized to evaluate the relationship between these two cancers.

Methods: A retrospective chart review was conducted for patients diagnosed with both GIST and PM between July 2010 and June 2021. Patient demographics, past tumor history, intraoperative reports, cross-sectional imaging, peritoneal cancer index (PCI) scoring, somatic next-generation sequencing (NGS) analysis, and histology were reviewed.

Results: Of 137 patients who underwent primary GIST resection from July 2010 to June 2021, 8 (5.8%) were found to have synchronous PM, and 4 patients (50%) had additional cancers and/or benign tumors. Five (62.5%) were male, and the median age at GIST diagnosis was 57 years (range: 45-76). Seventy-five percent of GISTs originated from the stomach. Of the eight patients, one patient had synchronous malignant mesothelioma (MM), and the remaining had well-differentiated papillary mesothelioma (WDPM), which were primarily located in the region of the primary GIST (89%). The median PCI score was 2 in the WDPM patients. NGS of GIST revealed oncogenic KIT exon 11 (62.5%), PDGFRA D842V (25%), or SDH (12.5%) mutations, while NGS of the MM revealed BAP1 and PBRM1 alterations.

Conclusions: One in 17 GIST patients undergoing resection in this series have PM, which is significantly higher than expected if these two diseases were considered as independent events. Our results indicate that synchronous co-occurrence of GIST and PM is an underrecognized finding, suggesting a possible relationship that deserves further investigation.

FIG. 1

GIST and PM characterization. A Co-mutation plot of patient data, cancer history, GIST and PM clinicopathological features, tumor genomic analyses, and germline genetic analyses. Data for each patient is listed in columns by case number, and are color-coded according to the legend. B Tabulation of NGS tumor panel results for each tumor and/or germline analyzed. Columns represent data for each patient that are subdivided into columns for the specific NGS assay conducted. Rows represent the tissue used for each NGS panel

FIG. 2

Anatomical map of Peritoneal Cancer Index (PCI) for each patient. PCI subscores (0, 1, 2, 3) in each abdominal/pelvic region are shown for each patient. Dark blue indicates a regional subscore of 3, medium blue indicates a regional subscore of 2, light blue indicates a regional subscore of 1, and white indicates a regional subscore of 0. *Note only 6 of the 13 PCI regions were explored in patient 5 due to laparoscopic cytoreduction